Effects of load distribution exerting on coal pillars on the stress and energy distribution of the floor strata

A theoretical analysis was conducted to establish a mathematical model of stress calculation in floor strata when the coal pillars are under arbitrary linear loading. It was shown that the distribution forms of stress and energy were the same, but the effect of the uniform loading on stress and energy value was greater than the bilinear loading condition under the same peak loading and elevation position. Within a certain critical distance from the bottom of the pillar, the vertical stress and energy density were mainly affected by the overlying single pillar action, but were gradually affected by the interactions between the multiple pillars beyond this critical distance. The horizontal stress was more vulnerable to the interactions of the multiple pillars under different loading conditions; then a method of the segmented straightening of the actual loading curve for the coal pillars on the stress calculation was proposed.